The public broadband switching network (VBN) of the German Bundespost permits transmission of image and voice in television quality at a bit rate of 140 mbit/s. The VBN represents a broadband direct dial network for a large number of subscribers with broadband terminals, such as video telephones and video conferencing equipment. Each subscriber is linked to the VBN via a subscriber connection unit TAE which converts the 140 mbit/s signals into audio, video, and data signals. The TAE contains function modules for control, A/D converters, multiplexers/demultiplexers, and line termination units, with the TAE controller being available for call setup. By means of such a VBN connection, it is also possible to operate a private automatic branch exchange having a plurality of user stations ("Automatic Direct Dialing Instead of Person-to-Person Calling", by E. Fischer and P. Pernsteiner, FUNKSCHAU, Vol. 5 (1989), p 30 ff.)